Re: kernel-doc overly verbose with V=0

[Jacob Keller <jacob.e.keller@intel.com>]

On 3/25/2026 4:50 AM, Mauro Carvalho Chehab wrote:
> On Tue, 24 Mar 2026 13:37:39 -0700
> Jacob Keller <jacob.e.keller@intel.com> wrote:
> 
>> Hi,
>>
>> I recently saw some strange behavior with the Python kernel-doc. I was
>> seeing the verbose info lines from the kernel-doc script, i.e.:
>>
>>> Info: ice_ptp_hw.c:5377 Scanning doc for function ice_cgu_get_pin_freq_supp
>>> Info: ice_ptp_hw.c:5406 Scanning doc for function ice_cgu_get_pin_name
>>> Info: ice_ptp_hw.c:5441 Scanning doc for function ice_cgu_state_to_name
>>> Info: ice_ptp_hw.c:5463 Scanning doc for function ice_get_dpll_ref_sw_status
>>> Info: ice_ptp_hw.c:5505 Scanning doc for function ice_set_dpll_ref_sw_status
>>> Info: ice_ptp_hw.c:5544 Scanning doc for function ice_get_cgu_state
>>> Info: ice_ptp_hw.c:5612 Scanning doc for function ice_get_cgu_rclk_pin_info
>>> Info: ice_ptp_hw.c:5671 Scanning doc for function ice_cgu_get_output_pin_state_caps
>>> Info: ice_ptp_hw.c:5733 Scanning doc for function ice_ptp_lock
>>> Info: ice_ptp_hw.c:5770 Scanning doc for function ice_ptp_unlock
>>> Info: ice_ptp_hw.c:5782 Scanning doc for function ice_ptp_init_hw
>>> Info: ice_ptp_hw.c:5811 Scanning doc for function ice_ptp_write_port_cmd
>>> Info: ice_ptp_hw.c:5834 Scanning doc for function ice_ptp_one_port_cmd
>>> Info: ice_ptp_hw.c:5866 Scanning doc for function ice_ptp_port_cmd
>>> Info: ice_ptp_hw.c:5901 Scanning doc for function ice_ptp_tmr_cmd
>>> Info: ice_ptp_hw.c:5934 Scanning doc for function ice_ptp_init_time
>>> Info: ice_ptp_hw.c:5986 Scanning doc for function ice_ptp_write_incval
>>> Info: ice_ptp_hw.c:6035 Scanning doc for function ice_ptp_write_incval_locked
>>> Info: ice_ptp_hw.c:6056 Scanning doc for function ice_ptp_adj_clock
>>> Info: ice_ptp_hw.c:6107 Scanning doc for function ice_read_phy_tstamp
>>> Info: ice_ptp_hw.c:6134 Scanning doc for function ice_clear_phy_tstamp
>>> Info: ice_ptp_hw.c:6164 Scanning doc for function ice_ptp_reset_ts_memory
>>> Info: ice_ptp_hw.c:6183 Scanning doc for function ice_ptp_init_phc
>>> Info: ice_ptp_hw.c:6215 Scanning doc for function ice_get_phy_tx_tstamp_ready
>>> Info: ice_ptp_hw.c:6247 Scanning doc for function ice_check_phy_tx_tstamp_ready
>>> Info: ice_ptp_hw.c:6273 Scanning doc for function ice_ptp_config_sfd
>>> Info: ice_ptp_hw.c:6293 Scanning doc for function refsync_pin_id_valid  
>>
>> I didn't understand why I was seeing this as it should only be happening
>> if running kernel-doc in verbose mode. Then I discovered I had set
>> KBUILD_VERBOSE=0 in my environment.
>>
>> The python kernel-doc implementation reads this in the __init__ for
>> KernelFiles() on line 165:
>>
>>>         if not verbose:
>>>             verbose = bool(os.environ.get("KBUILD_VERBOSE", 0))  
>>
>> After some debugging, I realized this reads KBUILD_VERBOSE as a string,
>> then converts it to a boolean using python's standard rules, so "0"
>> becomes true, which enables the verbose output.
> 
> Looking at tools/docs/sphinx-build-wrapper, it implements verbosity
> by doing:
> 
> 	verbose = bool(os.environ.get("KBUILD_VERBOSE", "") != "")
> 
> which will also have the same problem as the one you detected.
> 

Yep.

> Perhaps the right fix would be to first convert to int then to bool
> on both places, in a way that "" will also be handled properly.
> Perhaps with:
> 
> 	try:
> 	    verbose = bool(int(os.environ.get("KBUILD_VERBOSE", 0)))
> 	except ValueError:
> 	    # Handles an eventual case where verbosity is not a number
> 	    # like KBUILD_VERBOSE=""
> 	    verbose = False
> >> This is in contrast to the (now removed) kernel-doc.pl script which
>> checked the value for a 1:
>>
>>>  if (defined($ENV{'KBUILD_VERBOSE'}) && $ENV{'KBUILD_VERBOSE'} =~ '1')   
>> The same behavior happens if you assign V=0 on the command line or to
>> any other non-empty string, since when V is set on the command line it
>> sets KBUILD_VERBOSE.
> 
> That's funny... we did test make V=0 htmldocs / make V=1 htmldocs 
> 

Strange. The Makefile does this:

ifeq ("$(origin V)", "command line")
  KBUILD_VERBOSE = $(V)
endif

I can see KBUILD_VERBOSE=0 from the top level Makefile, but you're right
it doesn't seem to trigger the environment variable..

> It sounds that the problem is only if you explicitly set it without
> relying on gnu make.
> 

Adding some warn prints I do see the Makefile sets KBUILD_VERBOSE=0 when
you do V=0.. and it has an export clause for KBUILD_VERBOSE

Oh, it might be your particular build doesn't have W=1 so checkdoc isn't
being defined and thus kernel-doc isn't running?

If I do "make W=1 V=0" I do actually see these lines:

> Info: ../drivers/pci/pci.c:3646 Scanning doc for function pci_acs_init
> Info: ../drivers/pci/pci.c:3663 Scanning doc for function pci_enable_atomic_ops_to_root
> Info: ../drivers/pci/pci.c:3746 Scanning doc for function pci_release_region
> Info: ../drivers/pci/pci.c:3772 Scanning doc for function __pci_request_region
> Info: ../drivers/pci/pci.c:3820 Scanning doc for function pci_request_region
> Info: ../drivers/pci/pci.c:3841 Scanning doc for function pci_release_selected_regions
> Info: ../drivers/pci/pci.c:3879 Scanning doc for function pci_request_selected_regions
> Info: ../drivers/pci/pci.c:3894 Scanning doc for function pci_request_selected_regions_exclusive
> Info: ../drivers/pci/pci.c:3910 Scanning doc for function pci_release_regions
> Info: ../drivers/pci/pci.c:3925 Scanning doc for function pci_request_regions
> Info: ../drivers/pci/pci.c:3944 Scanning doc for function pci_request_regions_exclusive
> Info: ../drivers/pci/pci.c:4026 Scanning doc for function pci_remap_iospace
> Info: ../drivers/pci/pci.c:4062 Scanning doc for function pci_unmap_iospace
> Info: ../drivers/pci/pci.c:4097 Scanning doc for function pcibios_setup
> Info: ../drivers/pci/pci.c:4109 Scanning doc for function pcibios_set_master
> Info: ../drivers/pci/pci.c:4136 Scanning doc for function pci_set_master
> Info: ../drivers/pci/pci.c:4150 Scanning doc for function pci_clear_master
> Info: ../drivers/pci/pci.c:4160 Scanning doc for function pci_set_cacheline_size
> Info: ../drivers/pci/pci.c:4198 Scanning doc for function pci_set_mwi
> Info: ../drivers/pci/pci.c:4229 Scanning doc for function pci_try_set_mwi
> Info: ../drivers/pci/pci.c:4248 Scanning doc for function pci_clear_mwi
> Info: ../drivers/pci/pci.c:4268 Scanning doc for function pci_disable_parity
> Info: ../drivers/pci/pci.c:4285 Scanning doc for function pci_intx
> Info: ../drivers/pci/pci.c:4310 Scanning doc for function pci_wait_for_pending_transaction
> Info: ../drivers/pci/pci.c:4326 Scanning doc for function pcie_flr
> Info: ../drivers/pci/pci.c:4366 Scanning doc for function pcie_reset_flr
> Info: ../drivers/pci/pci.c:4443 Scanning doc for function pci_pm_reset
> Info: ../drivers/pci/pci.c:4497 Scanning doc for function pcie_wait_for_link_status
> Info: ../drivers/pci/pci.c:4527 Scanning doc for function pcie_retrain_link
> Info: ../drivers/pci/pci.c:4592 Scanning doc for function pcie_wait_for_link_delay
> Info: ../drivers/pci/pci.c:4642 Scanning doc for function pcie_wait_for_link
> Info: ../drivers/pci/pci.c:4679 Scanning doc for function pci_bridge_wait_for_secondary_bus
> Info: ../drivers/pci/pci.c:4818 Scanning doc for function pci_bridge_secondary_bus_reset
> Info: ../drivers/pci/pci.c:5077 Scanning doc for function __pci_reset_function_locked
> Info: ../drivers/pci/pci.c:5135 Scanning doc for function pci_init_reset_methods
> Info: ../drivers/pci/pci.c:5167 Scanning doc for function pci_reset_function
> Info: ../drivers/pci/pci.c:5214 Scanning doc for function pci_reset_function_locked
> Info: ../drivers/pci/pci.c:5252 Scanning doc for function pci_try_reset_function


>> Of course, I can remove KBUILD_VERBOSE from my environment, I'm not
>> entirely sure when or why I added it.
>>
>> Would think it would make sense to update the kdoc_files.py script to
>> check and interpret the string value the same way the perl script used
>> to? It seems reasonable to me that users might set "V=0" thinking that
>> it disables the verbosity. Other verbosity checks are based on the
>> string containing a 1,
> 
> kernel-doc has a set of "-W" flags to control its verbosity. Direct
> support for KBUILD_VERBOSE was added there just to make it bug-compatible
> with kernel-doc.pl when building via Makefile.
> 

Right.

> Yet, as using it via "make htmldocs" don't use "-W", IMO it makes
> sense to ensure that "-Wall" is enabled if V=1.
> 

We enable -Wall if KBUILD_EXTRA_WARN contains a 2:

ifeq ($(KBUILD_EXTMOD),)
ifneq ($(KBUILD_EXTRA_WARN),)
  cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(PYTHON3) $(KERNELDOC) -none
$(KDOCFLAGS) \
        $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
        $<
endif
endif

If KBUILD_EXTRA_WARN has 2 we do -Wall, and if its any non-zero value we
enable checkdoc. KBUILD_VERBOSE is handled internally to the script so
not part of the Make invocation.

So V=0 only manifests if KBUILD_EXTRA_WARN is set.

We set KBUILD_EXTRA_WARN in top level:

ifeq ("$(origin W)", "command line")
  KBUILD_EXTRA_WARN := $(W)
endif

export KBUILD_EXTRA_WARN

>> (some even use 2 for even more printing).
> 
> Documentation had support for V=2, but this was dropped on this
> commit:
> 	c0d3b83100c8 ("kbuild: do not print extra logs for V=2")
> 

Looks like there's some stale leftover bits then:

#
# If KBUILD_VERBOSE contains 1, the whole command is echoed.
# If KBUILD_VERBOSE contains 2, the reason for rebuilding is printed.
#
# To put more focus on warnings, be less verbose as default
# Use 'make V=1' to see the full commands
I don't have strong opinions either way.


>> I'm not entirely sure what the best implementation for python is to
>> avoid this misinterpretation, so I haven't drafted a proper patch yet.
> 
> Perhaps something like the patch below (untested).
> 

The patch seems reasonable, though I don't know about the enabling other
errors, as those are controlled by W=2 right now. I don't personally
have objections to enabling them with V as well, but others might?

Thanks,
Jake